Seventh seed Marin Cilic swept into the fourth round at Wimbledon with a 6-4 7-6(3) 6-4 win over American Steve Johnson to end an imperious opening week with a third consecutive straight sets victory.

The big-serving Croat took his aces tally to 63 for the tournament as he ended Johnson's Wimbledon run and underlined his own status as one of the main challengers to the established favourites.

Cilic, the 2014 US Open champion, is one of only two people, alongside Stan Wawrinka, to have won a grand slam in the last seven years outside of the game's dominant quartet of Roger Federer, Rafa Nadal, Novak Djokovic and Andy Murray.

Having reached the final at Queen's in the traditional Wimbledon warmup, his grasscourt game is in good shape and he eased past Johnson with minimum fuss.

The Croat took the first set when he broke in the 10th game and claimed the second in a tiebreak

After both players struggled to hold serve at the start of the third, Cilic took control before wrapping up the contest when the American dumped a forehand return into the net.

Murray meanwhile was involved in a late-night thriller against Italian showman Fabio Fognini to book his spot in the fourth round with a 6-2 4-6 6-1 7-5 victory.

The Wimbledon champion looked almost certain to be dragged into a fifth set by Fognini when he trailed 5-2 in the fourth, but he showed his mettle to save five set points and win five straight games to wrap up victory in two hours 39 minutes.

Next up for Cilic is Roberto Bautista Agut, who reached the fourth round with a shock victory over Japanese ninth seed Kei Nishikori.

The 29-year-old Bautista Agut proved too solid for a listless Nishikori, winning 6-4 7-6(3) 3-6 6-3 on Court Three.

Nishikori paid the price for failing to take his break point chances in the first set, especially at 4-4 when Bautista Agut saved one with a crisp forehand winner.

The Spaniard broke in the next game to take the opening set.

It was a similar story in the second set with Nishikori unable to convert any of the five break point chances that came his way before succumbing in a tiebreak.

Nishikori, who has never flourished on grass and is yet to go past the fourth round at Wimbledon, did battle back to take the third set but faltered in the fourth as Agut moved through to a last-16 showdown with Cilic.